1. Field of the Invention
The present invention relates to a portable display device having a liquid crystal display device, and more particularly to a portable display device capable of preventing the ambient temperature of a light source provided in a liquid crystal display device from being concentratedly raised.
2. Description of the Related Art
Recently, various flat panel display (FPD) devices capable of reducing weight and volume, which are disadvantages of a cathode ray tube display device, have been developed. As the flat panel display device, there are a liquid crystal display (LCD), a field emission display (FED), a plasma, display panel (PDP) and a light emitting display (LED), etc.
Here, a liquid crystal display device, which has advantages of a miniature size, light weight and low power, has been spotlighted as a replacement able to overcome the disadvantage of a conventional cathode ray tube, and it has been currently mounted on portable apparatus such as a cellular phone and a portable digital assistor (PDA), as well as small and large products such as a monitor and TV.
A contemporary portable display device is construed with a liquid crystal display panel, a backlight assembly, a bottom chassis, first and second printed circuit boards and a light-emitting display panel.
The liquid crystal display panel which displays a video image is constructed with a first substrate, a second substrate and a liquid crystal injected between the first and second substrates. An integrated circuit is inserted to one side of the second substrate.
The backlight assembly is constructed with light-emitting diodes, a light-emitting diode substrate, a light guide plate, a reflecting plate, optical sheets and a mold frame. The light-emitting diodes function as a light source for the liquid crystal display device and are mounted on the light-emitting diode substrate. The light-emitting diode substrate supplies the driving signals to the light-emitting diodes. At least one circuit component is mounted on the light emitting diode substrate. The light guide plate supplies the light generated from the light-emitting diodes to the liquid crystal display panel. Therefore, the light emitting diodes are disposed immediately adjacent to the light guide plate.
In the mold frame, the liquid crystal display panel, the light-emitting diode substrate constructed with the light-emitting diode which is a light source, the light guide plate, the reflecting plate, and the optical sheets, are received
In the contemporary portable display device, the liquid crystal display panel and integrated circuit may malfunction due to the heat generated when the light-emitting diodes emit light.
In particular, the contemporary portable display device is designed that the sides of each light-emitting diode excepting the side adjacent to the light guide plate are surrounded by the mold frame in order to prevent light leakage. In this case, however, the heat generated from the light-emitting diode fails to smoothly circulate so that the ambient temperature of the light-emitting diode continuously remains in a high lever.
In the region adjacent to the light-emitting diode where the liquid crystal display panel and the integrated circuit of the liquid crystal display panel are positioned, the liquid crystal display panel is partly heated so that the liquid crystal injected between the first and second substrates of the liquid display panel and the elements included in the integrated circuit may deteriorate due to the high ambient temperature of the light-emitting diode. In addition, in the case that at least one circuit component is mounted on the light-emitting diode substrate, this circuit component may also deteriorate due to the high temperature.
Therefore, we have discovered that it is necessary to prevent the ambient temperature of the light-emitting diode from being intensively raised by dispersing the heat generated from the light-emitting diode while the diode is acting as a light source for the liquid crystal display panel.